This invention relates to a WAN packet switching system, and more particularly to such a system using LAN type communication facilities.
Existing WAN based frame relay/packet switches have a hardware architecture based upon older connection oriented technology, such as TDM (Time division Multiplex). A connection oriented system is one where a discrete channel is set up through the network between the communicating parties, unlike a connectionless technology, such as frame relay, where packets are routed through the network on a statistical basis over virtual channels. Traditional switching technology relies on a centralized switching complex in which switching elements must be connected in a fully meshed configuration. Since the switches are TDM based, each switching element in the switch is connected using conventional TDM technology.
This type of architecture has a number of shortcomings. Firstly, a fixed amount of dedicated bandwidth is required between the switching elements. This is contrary to modern switching technologies, such as frame relay, which allows bandwidth to be shared between calls on a demand basis.
Secondly, such an architecture means that it is often difficult to expand the switching system off-premises. Particularly, the switching elements (since the system is TDM based and TDM bandwidth is usually very expensive) cannot be fully connected with the full bandwidth requirements of the system. In typical implementations of a distributed switching system, the switching elements are linked via a reduced speed TDM pipe.
Thirdly, the use of centralized switches means that customer traffic must be piped using TDM technology at reduced speeds to a central switching site. There the frames can be switched onto a higher capacity trunk. This means that customer-to-switch bandwidth is dedicated to the switching application.
Fourthly, typical implementations based upon TDM are not usually scaleable. This means that the switching elements cannot easily be added to increase the size of the switch to a higher capacity system. This is usually a result of the fact that less flexible (very expensive) TDM technology would be required to form a fully connected communications mesh between the switching elements.
Finally, TDM based switches are not designed to support switching interfaces of &gt;10 Mb/s. Using TDM technology to connect switching elements means using &lt;10 Mb/s bandwidth.
An object of the present invention is to provide a method of connecting connection-oriented switching elements together to form a scaleable, seamless, very fast, distributed WAN packet switch.